CVE-2026-64525

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> xfrm: move policy_bydst RCU sync from per-netns .exit to .pre_exit<br /> <br /> The struct pernet_operations docstring in include/net/net_namespace.h<br /> explicitly warns against blocking RCU primitives in .exit handlers:<br /> <br /> Exit methods using blocking RCU primitives, such as<br /> synchronize_rcu(), should be implemented via exit_batch.<br /> [...]<br /> Please, avoid synchronize_rcu() at all, where it&amp;#39;s possible.<br /> <br /> Note that a combination of pre_exit() and exit() can<br /> be used, since a synchronize_rcu() is guaranteed between<br /> the calls.<br /> <br /> xfrm_policy_fini() violates this: it calls synchronize_rcu() before<br /> freeing the policy_bydst hash tables (so no RCU reader is mid-<br /> traversal at free time), but runs from xfrm_net_ops.exit -- once per<br /> namespace -- so a cleanup_net() of N namespaces pays N full RCU<br /> grace periods serially.<br /> <br /> Use the documented pre_exit/exit split. Move the policy flush (and<br /> the workqueue drains it depends on) into a new .pre_exit handler;<br /> xfrm_policy_fini() then runs in .exit and frees the hash tables<br /> after the synchronize_rcu_expedited() that cleanup_net() guarantees<br /> between the two phases. Providing O(1) RCU grace periods per batch<br /> instead of O(N).<br /> <br /> Observed on Linux 6.18 with a workload doing unshare(CLONE_NEWNET)<br /> at ~13/sec sustained: cleanup_net() and the netns_wq rescuer kthread<br /> both stuck in xfrm_policy_fini()&amp;#39;s synchronize_rcu(), &gt;300k struct<br /> net accumulated in the cleanup queue, Percpu in /proc/meminfo climbed<br /> to 130+ GB on 256-CPU hosts, and memcg OOMs followed. setup_net and<br /> __put_net counts were balanced, ruling out a refcount leak.